This invention relates generally to internal pipe clamps.
Pipelines are laid extensively across the United States and other parts of the world in order to convey fluids or other material from one location to another. In the building of these pipelines numerous joints are laid end to end and welded together to form a conduit of the desired length and location.
The ends of adjacent pipe joints are welded together. The ends of these sections of pipe must be held during the welding operation. Internal welding clamps are generally used for this purpose. A frame supports a first spider ring and a second spider ring which are parallel to and spaced from each other. Each spider ring contains a plurality of radial pistons which when activated extend or retract radially through the spider ring. The outer end of these pistons contain a shoe or pad which contacts the inner surface of the pipe. One spider ring is in one section of pipe and the other in the other section, each near the ends of the pipe to be welded. By applying sufficient pressure to these pads on each spider ring the pipes are held substantially in fixed relationship with each other. Then welding operations may proceed. Pipe clamps are commercially available.
However, the presently available pipe clamps do not supply sufficient power or force to force the pipe into a round shape. The tensile strength of today's pipe is as high as X-70 and X-80 or more. The present clamping means cannot generate the force required to force out-of-round pipe into a "round" condition.
Some pipes are also "out-of-round." It is important to correct this. If one section of a pipe being welded is out-of-round in a different configuration than the other one then it is difficult to get a good weld. It is thus another object of this invention to provide clamps and supporting equipment which have sufficient power and force to force the pipe into a round or desired shape. This increases the welding efficiency.